1. Field of the Invention
The present invention relates generally to hand tools and, more specifically, to an improved hand tool for enabling a user to apply a greater degree of force through an axially repositionable shaft and further providing a heavy duty shaft adjustment mechanism which is recess mounted in an unobtrusive fashion within an elongate handle.
2. Description of the Prior Art
The prior art is well documented with numerous examples of hand tools and torque rod assemblies, each of which include some form of gripping handle member for axially receiving therein an elongate shaft portion displaying a tool engaging end and further having a mechanism of some sort for permitting selected axial repositioning of the shaft portion inwardly and outwardly of the handle. The professed advantage of such tools is to permit the shaft to be selectively and axially readjusted in inward and outward fashion relative to the outer gripping member in response to whatever space restrictions are presented in a surrounding operating environment.
U.S. Pat. No. 4,409,866, issued to McBride, teaches a tool assembly including a handle with a spring biased trigger means for permitting a selected insertable shank tool to be readjusted in an axial manner. The handle includes a through passageway substantially along its longitudinal axis and a cross section of an associated shank tool is sized so that it is slidably insertable within the handle. The tool handle further includes a body provided with a U-shaped trigger, a forward leg of which is movable in a transverse slot extending therethrough the passageway in and through the handle and includes an aperture formed therein which is adapted to permit the shank of the tool to pass therethrough. A plurality of spaced apart notches are formed along an underside surface of the shank tool and are selectively engaged by the forward leg portion. A rear trigger leg also includes a small aperture which is engaged by a pin and the "U" shaped trigger member is biased in an upward direction by a coil spring which is mounted within a recess open to an exterior of the handle and pressing upwardly against the underside surface of the base member of the "U" shaped trigger so that the trigger member is displaced a considerable distance above the level surface of the handle.
While disclosing an effective shaft repositioning device, the trigger assembly in McBride suffers from the shortcoming that the coil spring element which biases the trigger assembly projects outwardly from the recess mount a significant degree to a point exterior of the surface of the handle where it biases against the underside of the trigger. Having a coil spring in such an exposed arrangement is potentially harmful in that it could possibly slip out of alignment with the interconnecting base member of the "U" shaped trigger, causing the telescoping shaft to lose its retaining engagement with the handle. A further shortcoming of McBride involves the amount of biasing force that can be exerted by the spring and through the forward leg held within the selected notch in the shank without disengaging the shaft from the trigger. It is submitted that McBride does not teach a heavy-duty engaging mechanism for repositionally securing the shaft in axial fashion to the handle.
U.S. Pat. No. 2,592,978, issued to Trimboli, also discloses an interesting retractable tool device which includes a repositionable shank portion which is held within a handle. The shank includes a plurality of spaced apart and grooved slotted portions and a cylindrical head portion of the handle includes a spherical ball detent member which is biased inwardly by a spring so that it seats within a selected slotted portion. While illustrating an interiorly positioned spring member and detent, Trimboli suffers from the disadvantage that the spherical ball and spring arrangement also does not provide a heavy-duty type securing means for preventing inadvertent axial displacement of the shaft relative the gripping handle upon the application of an excessive degree of force, such as is necessary when loosening a partially corroded screw or like fastener.